Experience-dependent neural plasticity underlies drug addiction, complex, enduring behavioral changes; that result after drug use. Molecules rapidly regulated by neural activity are likely to be very important for initiating plasticity processes. Thus, their identification and characterization is of particular relevance for understanding cellular mechanisms that underlie behavioral change. This proposal seeks to combine novel methodologies to identify molecules subject to rapid, post-transcriptional regulation during establishment of long-term synaptic change. Recent technical advances made in the principal investigator's laboratory, in a: collaborator's group, and in the field of proteomics allow a new and direct approach to this largely unexplored, frontier in the study of plasticity. A novel procedure for inducing bursts of activity in the Drosophila nervous system is shown to initiate plasticity processes that lead to gene expression changes associated with-establishment of long-term plasticity. A technique called Differential Gel Electrophoresis (DIGE) has the ability to visualize and compare levels of about 5000 different protein elements from Drosophila heads. Combining these two techniques with mass spectrometry and more established molecular genetic approaches, the proposed experiments will identify proteins whose activities are rapidly regulated by post-translational covalent modification, by regulated protein turnover, or by induction of translation, following appropriate neural activity. Drosophila melanogaster is an excellent model organism for these analyses. The commonality of underlying mechanisms involved in plasticity regulation in mammals and insects is indicated by the functional conservation of almost all known regulators of plasticity in both phyla. However, the rate of progress of the proposed analyses in Drosophila is much faster, facilitated not only by its short generation time and facility for genetics, but also by novel resources from Drosophila genome projects, proteomic technologies and newly developed procedures for gene disruption, perturbation and replacement in vivo. The work is significant because it addresses a particularly poorly studied area, of fundamental, importance in synaptic remodeling events that underlie behavioral change. By identifying rapidly regulated, neuronal proteins the program may contribute new, early molecular markers of plasticity processes that underlie addiction. In addition, results from these experiments may identify new molecules to targets for pharmacological therapy.